Looks good but if its a diy I would make the box longer and and an emergency open overflow tube for a back up that way if you loose siphon your pump won't overflow the tank. Are you making it from acrylic?
I'd make the 8" front/back view longer, long enough to install a 3/4" emergency drain line. If you can fit the additional drain line into the 8" that would work too. Either way, I would definitely add an emergency drain line though.